In this section, we will explore how to view the commit history in a Git repository. Understanding the commit history is crucial for tracking changes, understanding the evolution of a project, and collaborating effectively with other developers.

1. Commit History: A record of all the changes made to the repository, including who made the changes and when.
2. Commit Hash: A unique identifier for each commit.
3. Commit Message: A description of the changes made in a commit.
4. Author and Date: Information about who made the commit and when it was made.

The git log command is the most commonly used command to view the commit history. It displays a list of commits in reverse chronological order (most recent first).

• --oneline: Displays each commit on a single line, showing the commit hash and the commit message.

  git log --oneline
  

  Example Output:

  1a2b3c4 Add new feature to the project
  0a1b2c3 Fix bug in the application
  

• --graph: Shows a graphical representation of the commit history.

  git log --graph
  

  Example Output:

  * commit 1a2b3c4
  | Author: John Doe <[email protected]>
  | Date:   Mon Oct 4 10:00:00 2023 -0400
  |
  |     Add new feature to the project
  |
  * commit 0a1b2c3
    Author: Jane Smith <[email protected]>
    Date:   Sun Oct 3 14:30:00 2023 -0400
  
        Fix bug in the application
  

• --since and --until: Filters commits based on a date range.

  git log --since="2023-10-01" --until="2023-10-04"
  

  Example Output:

  commit 1a2b3c4d5e6f7g8h9i0j1k2l3m4n5o6p7q8r9s0
  Author: John Doe <[email protected]>
  Date:   Mon Oct 4 10:00:00 2023 -0400
  
      Add new feature to the project
  

• -p: Shows the patch (diff) introduced in each commit.

  git log -p
  

  Example Output:

  commit 1a2b3c4d5e6f7g8h9i0j1k2l3m4n5o6p7q8r9s0
  Author: John Doe <[email protected]>
  Date:   Mon Oct 4 10:00:00 2023 -0400
  
      Add new feature to the project
  
  diff --git a/file.txt b/file.txt
  index 1234567..89abcdef 100644
  --- a/file.txt
  +++ b/file.txt
  @@ -1,3 +1,4 @@
   Line 1
   Line 2
  +Line 3
  

1. Objective: Use the git log command to view the commit history of a repository.
2. Steps:
   • Clone a sample repository (if you don't have one, you can use a public repository from GitHub).
   • Navigate to the repository directory.
   • Run the git log command to view the commit history.
   • Experiment with different options like --oneline, --graph, --since, --until, and -p.

1. Clone a sample repository:

   git clone https://github.com/octocat/Hello-World.git
   cd Hello-World
   

2. View the commit history:

   git log
   

3. View the commit history in a single line format:

   git log --oneline
   

4. View the commit history with a graphical representation:

   git log --graph
   

5. View commits made since October 1, 2023:

   git log --since="2023-10-01"
   

6. View the patch introduced in each commit:

   git log -p
   

• Mistake: Forgetting to navigate to the repository directory before running git log.

  • Tip: Always ensure you are in the correct directory by using cd <repository-directory>.

• Mistake: Using incorrect date formats with --since and --until.

  • Tip: Use the format YYYY-MM-DD for dates.

• Tip: Use q to exit the log view when it displays more information than fits on the screen.

In this section, we learned how to view the commit history using the git log command and its various options. Understanding the commit history is essential for tracking changes and collaborating effectively in a Git repository. In the next section, we will delve into branching and merging, which are crucial for managing different lines of development in a project.